Understanding of the human immune response after infection with Neisseria gonorrhoeae has remained elusive. In this project the types of circulating antibody responses and mucosal antibody responses to gonococcal infections will be studied and compared in order to develop a more thorough understanding of these responses and their potential significance in protection against gonococcal infection. Immune responses in three groups of patients with uncomplicated gonococcal infection will be studied prospectively: Group I, patients with repeated gonococcal infection (recidivists); Group II, patients with their first gonococcal infection; Group III, never-infected controls. Additionally, immune responses in a selected group of patients with disseminated gonococcal infections will be analyzed to help develop a more complete understanding of interaction between specific classes of immunoglobulins, complement and N. gonorrhoeae. Serums and purified serum immunoglobulins from patients in each group will be analyzed for bactericidal and opsonic activity against selected laboratory and wild strains of gonococci, and for activity against the patients' infecting strains using assay systems which have already been developed. Vaginal or urethral secretions, saliva, and possibly tears, will be collected and tested for serum and secretory immunoglobulin content. The secretions and immunoglobulin fractions obtained from the secretions will be tested for strain specific bactericidal and opsonic activity. Results of these assays will be compared to determine the significance of the patients circulatory and secretory immunoglobulin responses to gonococcal infections.